The present disclosure relates to a pin assembly.
The present invention concerns the field of fixings, and particularly, but not exclusively, fixings for aircraft. More particularly, but not exclusively, this invention concerns a pin assembly comprising a pin for supporting a rotating part, the pin defining a pin axis, and a nut, defining a nut axis and having a screw threaded portion which mates with the screw threaded portion of the pin.
The invention also concerns a fixing assembly, landing gear actuation mechanism, aircraft, method of manufacturing and a kit of parts.
A first prior art pin assembly for an aircraft comprises a pin, onto which a nut is screw threaded. The nut is screwed onto the pin to a required torque. Once this torque level has been applied and the nut is in that orientation, a hole is drilled through the pin and nut at the same time. This hole is used for a cross-bolt, so that the nut is secured to the pin at that torque level.
There are a number of problems with this arrangement. Firstly, the pin and nut are not interchangeable—in other words, if you want to replace the nut, you have to replace the pin as well and vice versa. Another problem is that there are a lot of stages to achieving this assembly and can make aircraft assembly more time consuming and expensive. Also, even if this method is carried out, it still can lead to misalignment between the pin and nut holes so that the cross-bolt cannot be used.
In a second prior art pin assembly, the locking nut comprises locking “castellations” on its outer end. A locking ring, with corresponding castellations, is placed around the pin to mate with the nut. The locking ring also has internal splines which mate with splines on the pin. Once the locking ring is fitted, bolts parallel to the pin axis are used to secure the locking ring to the locking nut. The ration of the number of holes in the locking ring and locking nut to the number of splines on the locking ring and pin is 1:3.
There are also problems with this arrangement. For example, the torque the nut is to be screwed onto the pin to cannot be accurately controlled as the nut has to end up in an orientation that allows the locking nut to mate with it whilst also mating with the pin splines. Hence, often, the locking nut is slightly looser or tighter than is ideal.
A third pin assembly arrangement comprises a pin with splines on it. A spline collar is placed on these pin splines to act as a washer. The pin also comprises a threaded portion outside of the splines and a nut is screwed onto this thread of the pin. The nut comprises recesses on its outer end. These recesses are like divets in the edge of the nut and have a width slightly larger than the diameter of a cross-bolt. Once the nut is thread onto the pin, the cross bolt is used to go through a pair of the divets and also through a corresponding pair of holes in the pin.
This arrangement also suffers from the problem that the orientation (and therefore torque level) of the nut on the pin cannot be accurately controlled. This is because the nut has to end up in an orientation that allows the nut divets to line up with the pin holes. Hence, often, the nut is slightly looser or tighter than is ideal.
The present invention seeks to mitigate the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved pin of fixing assembly.